In architecture, when demarcating moldings and leveling the ceiling with the ground, keeping a tilt meter horizontal to the ground all the time is an important issue. Reference is made to FIG. 1 illustrating a conventional leveling device in a tilt meter. As shown in FIG. 1, the plumb 102 is always perpendicular to the horizontal by gravity. Such a tilt meter can be used on any kind of ground, and since the plumb 102 is always perpendicular to the horizontal by gravity, the laser scanning apparatus associated with the plumb can indicate the horizontal status precisely. Although determining the horizontal by the plumb is a simple and effective method, the horizontal status can be acquired only after the swinging plumb becomes still. The usefulness of this kind of leveling device is therefore not optimum. Furthermore, the location of the plumb 102 of the conventional leveling device is not stationary during use. Thus, the laser beam at a distance trembles and the precision of the device is thus adversely affected.
Another kind of laser tilt meter exists which determines the horizontal by using a level-adjusting apparatus comprising a tilt sensor associated with a laser transmitter to project horizontal rays of light. Tilt sensors can be classified into two kinds: the single-axis tilt sensor and the dual-axis tilt sensor. The single-axis tilt sensor measures the slant of one direction, whereas the dual-axis one estimates the slant of a plane. How the tilt sensor works is illustrated in FIG. 2. It is known that the conductivity between two electrodes is proportional to the length of electrode immersed in an electrolyte. Even if the ground is not horizontal, the surface of the electrolyte in the tilt sensor remains level due to gravity. The electrolyte is electrically conductive, and since the conductivity between the two electrodes is proportional to the length of electrode immersed in the electrolyte, the resistance changes in proportion to the tilt angle. Therefore, the slant of the tilt sensor is derived from the resistance corresponding to the tilt angle.
However, in the level-adjusting apparatus, if the tilt sensor has been used for a long time, it will become unstable and consume more power. Furthermore, the present laser tilt meters do not have laser-beam-locking functionality. When the user moves the level-adjusting apparatus, the system self-adjusts automatically and points to the level again. Therefore, the apparatus cannot be used in other applications.